Occlusion device

ABSTRACT

A catheter includes a detachable tip assembly that when detached from the catheter may be used to occlude a body lumen or vessel. The detachable distal tip assembly may include an inflatable balloon disposed over and secured to a tubular member. The inflatable balloon may be in fluid communication within an inflation lumen extending within the catheter body. Upon reaching a target site within a body lumen or vessel, the detachable distal tip assembly may be released from the distal end of the catheter upon inflation of the balloon to a predetermined size.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims the benefit ofpriority to, U.S. patent application Ser. No. 14/615,051, filed Feb. 5,2015, which claims the benefit of priority under 35 U.S.C. § 119 to U.S.Provisional Application Ser. No. 61/936,653, filed Feb. 6, 2014, thedisclosures of which are herein incorporated herein by reference intheir entirety.

TECHNICAL FIELD

This disclosure relates to endovascular devices, and more particularly,to vaso-occlusive devices for the occlusion of body lumens and cavities.

BACKGROUND

In many clinical situations, blood vessels are occluded for a variety ofpurposes, such as to control bleeding, to prevent blood supply totumors, and to block blood flow within an aneurysm. Vaso-occlusivedevices have been used in the treatment of aneurysms. Vaso-occlusivedevices are surgical implants placed within blood vessels or vascularcavities, typically by the use of a catheter, to form a thrombus andocclude the site. For instance, an aneurysm may be treated byintroduction of a vaso-occlusive device through the neck of theaneurysm. The thrombogenic properties of the vaso-occlusive device causea mass to form in the aneurysm and alleviate the potential for growth ofthe aneurysm and its subsequent rupture. Other diseases, such as tumors,may also be treated by occluding the blood flow to a target area.

SUMMARY

This disclosure relates to endovascular devices, and more particularly,to vaso-occlusive devices for the occlusion of body lumens and cavities.In one illustrative embodiment, a medical device can include: a maincatheter body extending from a proximal end to a distal end; aninflation lumen extending within the main catheter body; a distal tipassembly releasably coupled to the distal end of the main catheter body;and a release mechanism coupled to the distal end of the main catheterbody. In some embodiments, the distal tip assembly can include a tubularmember defining a lumen extending from a proximal end to a sealed distalend, the tubular member including a plurality of apertures formed in anouter surface thereof, and an inflatable balloon disposed over andsecured to the tubular member, and the release mechanism can include twoor more retaining members extending distally away from the distal end ofthe main catheter body and engaging an outer surface of the inflatableballoon when the distal tip assembly is coupled to the distal end of themain catheter body prior to deployment. The retaining members can beconfigured such that upon expansion of the inflatable balloon, theretaining members are flexed outward and away from the main catheterbody until the distal tip assembly including the inflatable balloon isreleased from the main catheter body.

In another illustrative embodiment, a catheter assembly includes: acatheter having an elongated catheter shaft including an outer tubularmember having a plurality of apertures defined therein disposed over aninner tubular member, the inner tubular liner defining at least onelumen extending from a proximal end to a distal end of the inner tubularmember, wherein a distal region including the distal end of the innertubular liner extends beyond a distal end of the outer tubular member ofthe elongated catheter shaft; and an occlusion device releasablyattached to the distal end of the outer tubular member of the cathetershaft. The occlusion device can include a tubular member defining alumen extending from an open proximal end to a sealed distal end, thetubular member including a plurality of apertures formed in an outersurface thereof, and an inflatable balloon disposed over and secured tothe tubular member.

In yet another illustrative embodiment a method of delivering anocclusion device to a target location within a lumen of a patient's bodyincludes advancing a catheter assembly to a target location within thelumen of a patient's body. In some cases, The catheter assembly caninclude: an elongated catheter shaft including an outer tubular memberhaving a plurality of apertures defined therein disposed over an innertubular liner, the inner tubular member defining at least one lumenextending from a proximal end to a distal end of the inner tubularliner, wherein a distal region including the distal end of the innertubular liner extends beyond a distal end of the outer tubular member ofthe catheter shaft; and an occlusion device releasably attached to thedistal end of the outer tubular member of the catheter shaft. Theocclusion device can include a tubular member defining a lumen extendingfrom an open proximal end to a sealed distal end, the tubular memberincluding a plurality of apertures formed in an outer surface thereof,and an inflatable balloon disposed over and secured to the tubularmember. Additionally, the method can include inflating the inflatableballoon to at least a predetermined size, wherein inflation of theinflatable balloon to the predetermined size causes the occlusion deviceto be released from the distal end of the outer tubular member of thecatheter shaft; and withdrawing the catheter shaft in a proximaldirection away from the occlusion device to further release theocclusion device from the distal end of the catheter shaft. In othercases, the method can include controlling the inflation of the balloonsuch that that the inflatable balloon may be expanded to meet therequired size of the vessel in which the balloon is deployed.

The above summary of the present disclosure is not intended to describeeach embodiment or every implementation of the present disclosure.Advantages and attainments, together with a more complete understandingof the disclosure, will become apparent and appreciated by referring tothe following detailed description and claims taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of thefollowing detailed description of various embodiments in connection withthe accompanying drawings, in which:

FIG. 1 is a side plan view of a catheter in accordance with variousembodiments of the present disclosure:

FIG. 2 is a side, cross-sectional view of the catheter shown in FIG. 1in accordance with various embodiments of the present disclosure;

FIG. 3 is close-up, schematic view of a distal tip assembly coupled to adistal portion of the catheter shown in FIG. 1 in accordance with anembodiment of the present disclosure;

FIG. 4 is a cross-sectional view of the distal tip assembly coupled tothe distal portion of the catheter shown in FIG. 3;

FIG. 5 is a perspective view of a tubular member that forms a portion ofa distal tip assembly in accordance with an embodiment of the presentdisclosure;

FIGS. 6A and 6B are perspective views of a tubular member that forms aportion of a distal tip assembly in accordance with an embodiment of thepresent disclosure;

FIGS. 7A-7C show a distal tip assembly during different stages ofdetachment from a distal end of a catheter in accordance with anembodiment of the present disclosure;

FIGS. 8A and 8B are close-up, schematic view of a distal tip assemblycoupled to a distal portion of the catheter in accordance with anotherembodiment of the present disclosure; and

FIG. 9 is close-up, schematic view of a distal tip assembly coupled to adistal portion of the catheter in accordance with another embodiment ofthe present disclosure;

While the disclosure is amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit aspects of thedisclosure to the particular embodiments described. On the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the term “about” may be indicative asincluding numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

Although some suitable dimensions, ranges and/or values pertaining tovarious components, features and/or specifications are disclosed, one ofskill in the art, incited by the present disclosure, would understanddesired dimensions, ranges and/or values may deviate from thoseexpressly disclosed.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the disclosure. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

FIG. 1 shows an exemplary catheter 10 in accordance with variousembodiments of the present disclosure. In some cases, the catheter 10may be a guide or diagnostic catheter 10, and may have a length and anoutside diameter appropriate for its desired use, for example, to enableintravascular insertion and navigation. For example, when the catheter10 is adapted as a guide catheter, the catheter 10 may have a length ofabout 20 centimeters (cm)-250 cm and an outside diameter ofapproximately 1 French-10 French, depending upon the desiredapplication. In some cases, the catheter 10 may be a microcatheter thatis adapted and/or configured for use within small anatomies of thepatient. For example, the catheter 10 may be used to navigate to targetssites located in tortuous and narrow vessels such as, for example, tosites within the neurovascular system, certain sites within the coronaryvascular system, or to sites within the peripheral vascular system suchas superficial femoral, popliteal, or renal arteries. In some cases, thetarget site is a neurovascular site and may be located within apatient's brain, which is accessible only via a tortuous vascular path.However, it is contemplated that the catheter may be used in othertarget sites within the anatomy of a patient. An exemplary catheter thatmay be utilized in accordance with the various embodiments as describedherein is shown and described in U.S. Pat. No. 8,182,465, which isincorporated herein by reference in its entirety for all purposes.Additionally, although depicted as having a generally circularcross-sectional shape, it will be understood that the shaft 12 can haveother cross-sectional shapes or combinations of shapes without departingfrom the spirit of the disclosure. For example, the cross-sectionalshape of the generally tubular shaft 12 may be oval, rectangular,square, triangular, polygonal, and the like, or any other suitableshape, depending upon the desired characteristics.

As shown in FIG. 1, the catheter 10 can include an elongate cathetershaft 12 including a proximal portion 16 having a proximal end 18 anddistal portion 20 having a distal end 22. In some cases, a manifold 14may be connected to the proximal end 18 of the elongate shaft 12. Themanifold may include a hub 17 and/or other structures to facilitateconnection to other medical devices (e.g., syringe, stopcocks,Y-adapter, etc.) and to provide access to one or more lumens definedwithin the elongate shaft 12. In some cases, the hub 17 may be abifurcated hub, but this is not required. The manifold 14 may alsoinclude a strain relief portion adjacent the proximal end 18 of thecatheter shaft 12.

In some cases, the shaft 12 may include additional devices or structuressuch as inflation or anchoring members, sensors, optical elements,ablation devices or the like, depending upon the desired function andcharacteristics of the catheter 10. In some cases, the catheter 10 mayinclude a detachable tip assembly 24, as will be described in greaterdetail herein, coupled to the distal end 22 of the catheter shaft 12that, when detached from the shaft 12, may be used to occlude a vessel.For example, the detachable tip assembly 24 may include an inflatableballoon 32 that may be inflated and used to occlude a vessel at a targetsite within a patient's body. The balloon 32 may be inflated duringrelease of the detachable tip assembly 24 from the distal end 22 of thecatheter shaft, and may remain inflated upon deployment of thedetachable tip assembly 24 at the target site within the patient's body.

FIG. 2 is a partial, cross-sectional view of the catheter 10 shown inFIG. 1. As shown in FIG. 2, the shaft 12 can include an outerreinforcing member 26 disposed over an inner tubular member or liner 28defining at least one lumen 30. In some cases, the reinforcing member 26can be a generally tubular member including a proximal region 36 havinga proximal end 37 and a distal region 38 having a distal end 39. Thereinforcing member 26 can be disposed about at least a portion of theinner tubular member 28 at a location along the length of the shaft 12between proximal end 18 and distal end 22. The length of the reinforcingmember 26 may vary depending upon, for example, the length of the shaft12, the desired characteristics and functions of the catheter 10, andother such parameters. In some cases, as shown in FIG. 2, thereinforcing member 26 has a length such that it may be disposed over themajority of the length of the inner tubular member 28. In addition, thereinforcing member 26 has an inner diameter that is greater than theouter diameter of the inner tubular member 28. As such, in some cases,the reinforcing member 26 can be disposed about the inner tubular member28 (i.e. a portion of the inner tubular member 28 is disposed within thelumen of the reinforcing member) such that a space or gap is definedbetween at least a portion of the outer surface of the inner tubularmember 28 and the inner surface of the reinforcing member 26.

In many cases, the reinforcing member 26 can be adapted and/orconfigured to have a desired level of stiffness, torqueability,flexibility, bendability, and/or other characteristics. The desiredstiffness, torqueability, flexibility, bendability, or other suchcharacteristics of the reinforcing member 26 can be imparted or enhancedby the structure of the reinforcing member 26. For example, thereinforcing member 26 may include a thin wall tubular structure,including a plurality of apertures 44, such as grooves, cuts, slits,slots, or the like, formed in a portion of, or along the entire lengthof the tubular reinforcing member 26. Such structure may be desirablebecause it may allow reinforcing member 26, or portions thereof, to havea desired level of lateral flexibility as well as have the ability totransmit torque and pushing forces from the proximal region 36 to thedistal region 38. The apertures 44 can be formed in the reinforcingmember using any number of methods known to those of skill in the art.In some cases, the structure of the reinforcing member 26 is formed bycutting and/or removing portions of the tube to form apertures 44. Thenumber, spacing, location, arrangement, and/or orientation of theapertures 44 can be varied to achieve the desired characteristics. Insome cases, the apertures 44 may be formed such that one or more spinesor beams 29 are formed in the tubular reinforcing member 26 (FIG. 1). Insome cases, such spines or beams 29 can include portions of the tubularreinforcing member 26 that remain after the apertures 44 are formed inthe body of the tubular member. Such spines or beams 29 may act tomaintain a relatively high degree of torsional stiffness, whilemaintaining a desired level of lateral flexibility.

In addition to, or as an alternative to the structure of the reinforcingmember 26, the materials selected for reinforcing member 26 may bechosen so that it has the desired characteristics. For example,reinforcing member 26 may be formed of materials having a desiredmodulus of elasticity. The reinforcing member 26 may be formed of anymaterials suitable for use, dependent upon the desired properties of thecatheter 10. Some examples of suitable materials include metals, metalalloys, polymers, or the like, or combinations or mixtures thereof. Insome cases, the reinforcing member 26 may be fabricated from nitinoltubing to achieve the desired characteristics. Additionally, thereinforcing member 26 may be of, incorporate, or be coated, plated, orclad with a radiopaque or MRI safe imaging material to facilitateradiographic visualization or MRI safe imaging.

As shown in FIG. 2, the inner tubular member 28 can extend from a pointwithin the distal portion 20 to a point within the proximal portion 16of the catheter shaft 12. The length of the inner tubular member 28 mayvary, depending upon, for example, the length of the shaft 12, thedesired characteristics and functions of the catheter 10, and other suchparameters. In some cases, the inner tubular member 28 can extendsubstantially the entire length of the shaft 12. In some embodiments,the inner tubular member 28 can include a proximal portion 33 and adistal portion 35. The distal portion 35 of the inner tubular member 28may be any portion of the inner tubular member 28 that is extends in adistal direction beyond a distal end 39 of the reinforcing member 26,while the proximal portion 33 can be any portion of the inner tubularmember 28 that is disposed within, or is proximal to the distal end 39of reinforcing member 26. In some cases, the distal portion 35 of theinner tubular member 28 may extend beyond a distal end 39 of thereinforcing member 26 and into the distal tip assembly 24.

In some cases, the inner tubular member 28 may be multi-layered to suchthat the inner tubular member 28 has a desired shapeability,flexibility, steerability, atraumatic characteristics, and/or the liketo facilitate navigation through tortuous vascular pathways. Forexample, in some cases, a distal region of the inner tubular member 28may include an inner reinforcement layer such as a coil, braid or thelike and an outer layer, such as, for example, a polymer sleeve orlayer, disposed about the reinforcement layer of the distal region ofthe inner tubular member 28. Alternatively, the reinforcing coil orbraid may be embedded within a polymer sleeve or disposed betweenmultiple layers. In other cases, the inner tubular member 28 may bemulti-layered along a majority of its length, and may include an innerreinforcement layer such as a coil, braid or the like and an outerlayer, such as, for example, a polymer sleeve or layer, disposed aboutthe reinforcement layer. In other cases, the inner tubular member 28 maybe a braided tubular member and may be fabricated frompolytetrafluoroethylene (PTFE) or other similar material.

As shown in FIG. 2, the inner tubular member 28 may define at least onelumen 30. In some cases, the inner tubular member 28 may include twolumens. For example, the inner tubular member 28 may include a firstlumen for facilitating the passage of one or more guidewires and/or theinjection of a contrast fluid and or saline, and a second lumen fordelivering pressurized liquid such as, for example, an inflation fluidto a balloon 32 disposed over the detachable tip assembly 24. However,for the ease of illustration, only a single lumen 30 is shown in thefigure. It will be generally understood by those skilled in the art thatthe inner tubular member 28 may include any number of lumens, and in thecase of multiple lumens, that the lumens may have different diametersand/or cross-sectional shapes. In some cases, the lumen 30 of the innertubular member 28 may be in fluid communication with a lumen of thedetachable tip assembly 24 such that inflation medium is able to flowthrough the catheter shaft and into the detachable tip assembly 24,causing balloon 32 to inflate.

FIG. 3 is a close-up schematic view of the detachable distal tipassembly 24 coupled to a distal portion 20 of the catheter shaft 12.FIG. 4 is a cross-sectional view of the detachable tip assembly 24coupled to the distal portion 20 of the catheter shaft 12 shown in FIG.3. In some cases, the detachable tip assembly 24 includes an inflatableballoon 32 such that when the balloon 32 is inflated and the distal tipassembly 24 is detached from the catheter shaft 12, the distal tipassembly 24 forms an occlusion device at a target site within apatient's body such as, for example, a blood vessel.

The balloon 32 may be fabricated from any compliant material suitablefor use within the human body. In one example, the balloon may befabricated from polyethylene terephthalate (PET). In some cases, theballoon 32 may be configured to inflate from a collapsed configurationsuitable for delivery to the target site, within the body lumen orvessel, as shown in FIGS. 3 and 4, to an expanded configuration. In theexpanded configuration, the balloon 32 may be sized such that theballoon 32 contacts the inner walls of the body vessel or lumen in whichthe distal tip assembly is deployed. The balloon 32 may be inflateduntil it contacts and engages the inner walls of the vessel in which itis deployed such to form a fluid tight seal, occluding the vessel. Insome cases, because it is fabricated from a compliant material, theinflatable balloon 32 may be capable of conforming to the features ofthe inner surfaces of the vessel in which it is deployed.

As shown in FIGS. 3 and 4, the balloon 32 may be disposed over andattached to a tubular member 52 which also forms a portion of the distaltip assembly 24. In one example, the balloon 32 may be disposed over andattached to the proximal and distal ends 54, 56 of the tubular member52. In another example, the balloon 32 may be disposed over the tubularmember 52 such that it encloses the distal end 56 of the tubular member52 and is attached to the proximal end 54 of the tubular member 52.

FIGS. 5 and 6 are perspective views of an exemplary tubular member 52that may form a portion of the distal tip assembly 24 as shown in anyone of FIGS. 1-4. In many cases, the tubular member 52 may be fabricatedfrom nitinol tubing. Tubular member 52 may define a lumen 58 and mayinclude an open proximal end 54 (shown in FIGS. 4-6) for receiving aninflation fluid and a sealed distal end 56. In some cases, as shown inFIG. 4, when the distal tip assembly 24 is coupled to the distal end 22of the catheter shaft 12, the lumen 58 of the tubular member 52 can bein fluid communication with lumen 30 of the inner tubular member 28 suchthat inflation medium may flow through lumen 30 of the inner tubularmember 28 and into the lumen 58 of tubular member 52 of the distal tipassembly 24. In addition, tubular member 52 may include a plurality ofapertures 60 formed therein. The apertures 60 may be formed in thetubular member 52 such that they extend through the tubular member 52from an inner surface 62 to an outer surface 66 to allow the passage ofa fluid there through and into balloon 32, causing balloon 32 toinflate. In some cases, the plurality of apertures 60 may be evenlydistributed about an outer circumference of the tubular member 52 tofacilitate an even flow of fluid from out of the tubular member 52 andinto the balloon 32, which may facilitate an even and controlledinflation of balloon 32. The apertures 60 may have any shape that mayfacilitate fluid flow. In one example, the apertures 60 may be circular.In other cases, the apertures 60 may be rectangular slots or slitsformed in the tubular member 52.

In some cases, to maintain inflation of the balloon 32 upon detachmentof the distal tip assembly 24, the apertures 60 may be configured suchthey can be opened upon the introduction of an inflation fluid into thetubular member 52 and closed upon the cessation of fluid flow into thetubular member 52. For example, as shown in FIGS. 6A and 6B, each of theplurality of apertures may have a corresponding flap 64. The flaps 64can be configured to open upon the introduction of an inflation mediumthrough the apertures 60 and then close, upon the cessation of fluidflow. In some cases, the flaps 64 may be configured to open once theinflation medium has achieved or exceeded a predetermined pressure. Ifthe pressure has not reached a predetermined pressure, the flaps 64 willremain closed effectively sealing the apertures 60. As such, in somecases, the flaps 64 may function as one-way valves and thus, are capableof maintaining inflation of the balloon 32 when the distal tip assembly24 is deployed in a vessel. The flow of blood or other bodily fluid intothe lumen 58 of the tubular member 52 after deployment of the distal tipassembly 24 may be incapable of overcoming the pressure placed on theflaps 64 by the inflation medium contained within the balloon 32, thusthe flaps may remain closed when the distal tip assembly 24 is deployedin a vessel, maintaining the desired inflation of the balloon 32.

In some cases, as shown in FIG. 6A, the flaps 64 may be integrallyformed from the tubular member 52, or be formed as a unitary structurewith the tubular member 52, during the fabrication of apertures 60 suchthat when the flaps 64 are closed, they are substantially flush with anouter surface 66 of the tubular member 52. In other cases, the flaps 64may be formed in annular member 68 (Figured 6B) that is then bonded tothe outer surface 66 of the tubular member 52 adjacent to the apertures60 such that the flaps 64 are disposed over the apertures 60 toeffectively seal the apertures 60 when there is no fluid flow throughthe apertures 60. The material used to form the annular member 68 andthe flaps 64 may be the same material used to form the tubular member 52(e.g. nitinol). In another example, the annular member 68 and flaps 64may be fabricated from different material than was used to fabricate thetubular member 52. For example, the annular member 68 and flaps 64 maybe fabricated from a polymeric material or an elastomeric material suchas, for example, silicone. Alternatively, the apertures 60 may besufficiently shaped and sized such that they create sufficient surfacetension across the aperture openings when the balloon is inflated withinflation medium so as to prevent the backflow of inflation medium intothe tubular member 52.

Alternatively, the apertures 60 may be covered by a polymeric orelastomeric material that has a particular shape or size that isconfigured to perform as a one-way valve. For example, duckbill,umbrella, dispensing, access, Belleville, cross-slit and dome valuesmade from polymeric or elastomeric materials are all known in the art(e.g., Minivalve, Inc.).

Referring back to FIGS. 3 and 4, the catheter 10 may include a releasemechanism 70 coupled to the distal end 22 of the catheter shaft 12. Therelease mechanism may be used to releasably couple the distal tipassembly 24, including the inflatable balloon 32 disposed over tubularmember 52, to catheter 10 for delivery to a target site within apatient's body. In some cases, upon reaching a target site in a vessel,the release mechanism 70 may be configured to release the distal tipassembly 24 upon expansion of the inflatable balloon 32. In some cases,the release mechanism 70 may be secured to an outer surface of thedistal portion 35 of the inner tubular member 28 that extends beyond thedistal end of the outer reinforcing member 26. In other cases, therelease mechanism 70 may be secured to an outer surface of thereinforcing member 26. In still other cases, the release mechanism 70may be fabricated from the same nitinol tubing piece used to fabricatethe reinforcing member 26 such that the release mechanism 70 forms adistal end of the reinforcing member 26.

In some cases, as shown in FIGS. 3 and 4, the release mechanism 70 mayinclude one or more retaining members 72 that are configured to contactand frictionally engage an outer surface 74 of the balloon 32. The oneor more retaining members 72 may be supported by an annular ring 76 thatmay be secured to an outer surface of the inner tubular member 28, anouter surface of the outer reinforcing member 26, or integrally formedwith the outer reinforcing member 26, as described herein. In somecases, the one or more retaining members 72 may be integrally formedfrom the annular ring 76. In other cases, the one or more retainingmembers 72 may be bonded to or otherwise secured to the annular ring 76.The one or more retaining members 72 may be fabricated from any numberof suitable materials including nitinol and elastomeric materials. Theretaining members 72 may be fabricated such that they are capable ofplacing sufficient frictional forces on the distal tip assembly 24 so asto couple and secure the distal tip assembly 24 to the distal end 22 ofthe catheter shaft, even in the event of movement (linear or rotational)of the device within the vasculature. In addition, the retaining members72 may be fabricated such that they are sufficiently flexible such thatthey are capable of flexing outward and away from a longitudinal axis ofthe catheter 10 and the distal tip assembly 24 upon inflation of theballoon 32. In some case, the retaining members 72 may be flexible clipsor clamps.

In some cases, the release mechanism 70 may include a first pair offirst and second retaining members 72 that are disposed on oppositesides of the distal tip assembly 24. In some cases, the first and secondretaining members 72 may be disposed 180 degrees from one another aboutan outer circumference of the distal tip assembly 24. The releasemechanism 70 may also include a second pair of third and fourthretaining members 72 (of which one retaining member 72 is shown in FIG.3) which may be spaced away from the first pair of retaining members andalso disposed on opposite sides of the distal tip assembly 24. In somecases, the second pair of retaining members may be spaced about 90degrees away from the first pair of retaining members and located about180 degrees opposite from one another about an outer circumference ofthe distal tip assembly such that each of the four retaining membersmaybe located approximately 90 degrees from one another about an outercircumference of the distal tip assembly 24. As can be seen in FIGS. 3and 4, when the distal tip assembly 24 is coupled to the distal end 22of the shaft 12, the retaining members 72 contact and engage the outersurface 74 of the inflatable balloon 32 and consequently, the tubularmember 52 over which the balloon 32 is disposed, so as to secure thedetachable tip assembly 24 to the distal end 22 of the catheter shaft 12for delivery to a target site within a body lumen or vessel.

In some cases, as described herein and as shown in FIG. 4, a distalportion 35 of the inner tubular member 28 of the catheter shaft 12 mayextend into the distal tip assembly 24 such that the lumen 30 of thecatheter shaft 12 is in fluid communication with the lumen 58 of thetubular member 52 of the distal tip assembly 24. Inflation fluid may beintroduced into the lumen 30 via a fluid introduction port located inthe hub 17 of the catheter shaft 12. The inflation fluid may flowthrough the lumen 30 of the catheter shaft 12 defined by inner tubularmember 28 and into lumen 58 of the tubular member 52 of the distal tipassembly 24 where it then passes through apertures 60 and into balloon32 to inflate the balloon 32.

In some cases, the distal portion 35 of the inner tubular member 28 maybe disposed within the tubular member 52 of the distal tip assembly 24such that the outer surface 80 of the inner tubular member 28 contactsan inner surface 82 of the tubular member 52 of the distal tip assembly24. Passage of fluid through the distal portion 35 of the inner tubularmember 28 and into the lumen 58 of the tubular member 52 may cause aradial outward expansion of the distal portion 35 such that the outersurface 80 of distal portion 35 presses up against the inner surface 82of the tubular member 52 forming a temporary seal 86 between the distalportion 35 of the inner tubular member 28 and the tubular member 52. Insome cases, the distal portion 35 of the inner tubular member 28 may befabricated from a soft plastic material such as, for example, PEBAX, orsilicone, that facilitates its radial outward expansion upon passage ofa fluid therethrough. The distal portion 35 continues to increase theradial outward expansion forces placed on the inner surface 82 of thetubular member 52 during inflation of the balloon 32 which may furtherimprove the seal 86 between the inner tubular member 28 and the tubularmember 52 of the distal tip assembly 24. The temporary seal 86 formedbetween the outer surface 80 of the distal portion 35 of the innertubular member 28 and the inner surface 82 of the tubular member 52 mayaid in retaining the distal tip assembly 24 on the distal end 22 of thecatheter shaft 12 after the balloon 32 has been inflated to apredetermined size to effect release of the balloon from the releasemechanism 70. In some cases, after the release mechanism 70 hasdisengaged from the balloon 32, the balloon 32 may continue to beexpanded so as to achieve a size sufficient to occlude the vessel inwhich the distal tip assembly 24 is deployed. So long as fluid isflowing through the distal portion 35 of the inner tubular member 28 andinto the tubular member 52 of the distal tip assembly 24, the distal tipassembly 24 may still be retained on the distal end 22 of the cathetershaft 12 even after the release mechanism 70 has disengage from thedistal tip assembly 24. Once the balloon 32 is determined to havereached a size sufficient to occlude the vessel in which the distal tipassembly 24 is deployed, the pressure inside the catheter shaft 12 maybe released by the cessation of fluid flow, and the temporary seal 86formed between outer surface 80 of the distal portion 35 of the innertubular member 28 and the inner surface 82 of the tubular member 52 maybe released, facilitating withdrawal of the inner member from the distaltip assembly 24 and final detachment of the distal tip assembly 24 fromthe catheter shaft 12.

FIGS. 7A-7C is schematic views of a distal tip assembly, as describedherein, during different states of detachment from a distal end 22 of acatheter shaft 12. FIG. 7A shows the distal tip assembly 24 duringdelivery of the distal tip assembly 24 to a target site within a bodyvessel or lumen prior to introduction of an inflation medium into theballoon 32. During advancement of the distal portion 20 of the catheter10 at a target site within a body lumen or vessel, the balloon 32 may bein a collapsed configuration until the target site is reached. As shownin FIG. 7A, the retaining members 72 may be in contact with andfrictionally engage the outer surface 74 of the balloon 32 andconsequently, the tubular member 52 of the distal tip assembly 24 toretain the distal tip assembly 24 on the distal end 22 of the catheter10 during delivery. Upon reaching the target site, an inflation mediummay be introduced into a fluid delivery port located in the manifold 14of the catheter 10 (FIG. 1). The inflation medium may flow through thelumen 30 of the catheter shaft 12 defined by inner tubular member 28 andinto lumen 58 of the tubular member 52 of the distal tip assembly 24where it then passes through apertures 60 and into balloon 32 to inflatethe balloon 32. FIG. 7B shows the balloon 32 in a partially expandedconfiguration during inflation of the balloon 32. As can be seen in FIG.7B, the retaining members 72 are configured to flex outward and awayfrom a longitudinal axis of the catheter 10 and the distal tip assembly24 during inflation of the balloon 32. Upon expansion of the balloon 32to a predetermined size, the retaining members 72 may be configured todisengage from the balloon 32 and consequently, from the distal tipassembly 24, causing the distal tip assembly 24 to detach from thedistal end 22 of the catheter shaft. In some cases, additional fluid maycontinue to be delivered to the balloon 32 to continue to inflate theballoon to a size sufficient to achieve occlusion of the body vessel orlumen. The introduction of fluid is then ceased, causing any seal formedbetween the inner tubular member 28 of the catheter shaft 12 and thetubular member 52 of the distal tip assembly further effectingdetachment of the distal tip assembly 24 from the distal end 22 of thecatheter shaft 12, as shown in FIG. 7C. After the distal tip assembly 24has been deployed at the target site within the body vessel or lumen,the catheter 10 may be withdrawn from the patient's body.

In other cases, as shown in FIGS. 8A and 8B, the release mechanism 70may include a tubular segment 90 that may be disposed over the distalend 22 of the catheter shaft 12 and a proximal portion 92 of theinflatable balloon 32 so as to releasably couple the distal tip assembly24 to the distal end 22 of the catheter. The tubular segment 90 may bedisposed over the outer surface of the reinforcing member 26 or theouter surface of the distal portion 35 of the inner tubular member 28which extends beyond the distal end of the reinforcing member. In eitherexample, the tubular segment 90 may have a minimal wall thickness suchthat it maintains it a low profile when disposed on the catheter shaft12. In some cases, the tubular segment 90 may be fabricated from amaterial having sufficient flexibility such that at least the distalportion of the tubular segment 90 is capable of expanding as balloon 32inflates, as shown in FIG. 8B. Exemplary materials that may be used tofabricate the tubular segment 90 may include, but are not limited fromPEBAX, polyethylene terephthalate (PET), silicone, a polyurethane and/orthe like. In some cases, at least the distal portion 94 of the tubularsegment 90 may be configured to expand to a predetermined outer diameteras the balloon 32 inflates, whereupon reaching the pre-determined outdiameter, the tubular segment 90 may be configured to release theballoon 32 and consequently, the distal tip assembly 24. In some cases,the balloon 32 may continue to be inflated after release by the tubularsegment 90 until it has reached a size sufficient to occlude the vesselin which the distal tip assembly is deployed. After the balloon 32 hasbeen released, the tubular segment 90 may be configured to return to aninitial, non-expanded outer diameter, as shown in FIG. 8A, to facilitatewithdrawal of the catheter 10 from the patient's body.

In yet another example, as shown in FIG. 9, the release mechanism 70 mayinclude at least one pair of interlocking features 102, 104 that may beconfigured to releasably couple the distal tip assembly 24 to the distalend 22 of the catheter shaft 12. In some cases, a first locking feature102 may be formed within an annular member 106 and a second lockingfeature 104 may be coupled to or integrally formed with the proximal end54 of the tubular member 52 of the distal tip assembly 24. The annularmember 106 may be may be disposed over the outer surface of thereinforcing member 26 or the outer surface of the distal portion 35 ofthe inner tubular member 28 which extends beyond the distal end of thereinforcing member. The first and second locking features 102, 104 maybe configured to cooperate with one another to releasably attach theproximal end 54 of the tubular member 52 to the distal end 22 of thecatheter shaft. In some cases, the first locking feature 102 may be arecess formed within the annular member 106 having a shape correspondingto the shape the second locking feature 104, which extends away from theproximal end 54 of the tubular member 52. Additionally, a channel 108may be formed within the annular member adjacent the first lockingfeature 102 such that it facilitates detachment of the distal tipassembly 24 from the catheter shaft 12 via rotation of the cathetershaft. In some cases, the release mechanism 70 may include a second pairof interlocking features (not shown) located approximately 180 degreesopposite the first pair of interlocking features 102, 104 about an outercircumference of the catheter 10.

In use, after inflation of the balloon 32, a clinician may twist orapply torque to the proximal end of the catheter which is thentransferred down the catheter shaft 12 to cause release of themechanical interlock between the first and second locking feature 102,104. An example of such a torqueable catheter is Boston Scientific'sDirexion torqueable microcatheter. Inflation of the balloon 32 prior torelease of the release of the first and second locking features 102,104, may place enough of a resistive force on the release mechanism 70,such that the clinician may be able to push the distal end 22 of thecatheter shaft 12 forward as torque is applied to effectively cause thelocking features 102, 104 to disengage from one another.

Those skilled in the art will recognize that the present disclosure maybe manifested in a variety of forms other than the specific embodimentsdescribed and contemplated herein. Accordingly, departure in form anddetail may be made without departing from the scope and spirit of thepresent disclosure as described in the appended claims.

What is claimed is:
 1. A medical device, comprising: a main catheter body extending from a proximal end to a distal end; a distal tip assembly releasably coupled to the distal end of the main catheter body, the distal tip assembly including a tubular member defining a lumen extending from a proximal end to a distal end, and an inflatable balloon disposed over and secured to the tubular member; an inflation lumen in fluid communication with the inflatable balloon; and a release mechanism at the distal end of the main catheter body, the release mechanism comprising a tubular segment engaging an outer surface of the inflatable balloon when the distal tip assembly is coupled to the distal end of the main catheter body prior to deployment, wherein the tubular segment is configured such that expansion of the inflatable balloon expands at least a distal portion of the tubular segment outward and away from the main catheter body until the distal tip assembly including the inflatable balloon is released from the main catheter body.
 2. The medical device of claim 1, wherein the main catheter body comprises an outer member disposed over an inner tubular member.
 3. The medical device of claim 2, wherein the outer member comprises a nitinol tube having a plurality of apertures defined therealong.
 4. The medical device of claim 2, wherein the inner tubular member defines the inflation lumen.
 5. The medical device of claim 2, wherein a distal portion of the inner tubular member extends within the lumen defined by the tubular member of the distal tip assembly.
 6. The medical device of claim 1, wherein the lumen of the tubular member of the distal tip assembly is in fluid communication with the inflation lumen.
 7. The medical device of claim 6, wherein the tubular member includes a plurality of apertures formed in an outer surface thereof, and the inflation lumen is in fluid communication with the inflatable balloon through the apertures.
 8. The medical device of claim 7, wherein each of the plurality of apertures formed in the tubular member of the distal tip assembly comprises a corresponding flap disposed over the apertures, wherein when an inflation fluid is introduced into the tubular member the flaps move outward and away from the outer surface of the tubular member to facilitate passage of the fluid therethrough to inflate the balloon, and wherein after the balloon is inflated, the flaps close the apertures and maintain inflation of the balloon.
 9. The medical device of claim 1, wherein a proximal end and a distal end of the balloon is attached to the proximal end and the distal end of the tubular member such that the balloon has a substantially cylindrical shape upon inflation.
 10. The medical device of claim 1, wherein the distal end of the tubular member of the distal tip assembly is sealed.
 11. The medical device of claim 1, wherein the tubular segment is designed to release the distal tip assembly upon inflation of the inflatable balloon to a predetermined size.
 12. A medical device, comprising: a main catheter body extending from a proximal end to a distal end; a distal tip assembly releasably coupled to the distal end of the main catheter body, the distal tip assembly including a tubular member defining a lumen extending from a proximal end to a distal end, and an inflatable balloon disposed over and secured to the tubular member; an inflation lumen in fluid communication with the inflatable balloon; and release mechanism comprising a first locking feature associated with the distal end of the main catheter body, and a second locking feature associated with the proximal end of the distal tip assembly, wherein the distal tip assembly is releasably coupled to the main catheter body by mating surfaces of the first and second locking features prior to deployment, wherein the first and second locking features are configured such that upon rotation of the main catheter body relative to the distal tip assembly, the mating surfaces of the first and second locking features disengage to release the distal tip assembly from the main catheter body.
 13. The medical device of claim 12, wherein the first locking feature includes a recessed portion configured to receive a corresponding projection of the second locking feature.
 14. The medical device of claim 12, wherein the main catheter body is rotatable relative to the distal tip assembly and the first and second locking features are disengageable only after expansion of the inflatable balloon.
 15. The medical device of claim 12, wherein the tubular member includes a plurality of apertures formed in an outer surface thereof, and the inflation lumen is in fluid communication with the inflatable balloon through the apertures.
 16. The medical device of claim 15, wherein each of the plurality of apertures formed in the tubular member of the distal tip assembly comprises a corresponding flap disposed over and sealing the apertures, wherein when an inflation fluid is introduced into the tubular member the flaps move outward and away from the outer surface of the tubular member to facilitate passage of the fluid therethrough to inflate the balloon, and wherein after the balloon is inflated, the flaps close to seal the apertures and maintain inflation of the balloon.
 17. The medical device of claim 12, wherein a proximal end and a distal end of the balloon is attached to the proximal end and the distal end of the tubular member such that the balloon has a substantially cylindrical shape upon inflation.
 18. A method of delivering an occlusion device to a target location within a body lumen, the method comprising: advancing a catheter assembly to a target location within a body lumen, the catheter assembly comprising: a main catheter body extending from a proximal end to a distal end, a distal tip assembly releasably coupled to the distal end of the main catheter body, the distal tip assembly including an inflatable balloon disposed over an outer surface of the distal tip assembly, an inflation lumen extending within the main catheter body, and a release mechanism comprising a first locking feature associated with the distal end of the main catheter body, and a second locking feature associated with the proximal end of the distal tip assembly; inflating the inflatable balloon to at least a predetermined size; and rotating the main catheter body relative to the distal tip assembly to release the distal tip assembly.
 19. The method of claim 18, further comprising withdrawing the main catheter body from the body lumen.
 20. The method of claim 18, wherein the distal tip assembly includes a tubular member defining a lumen extending from a proximal end to a sealed distal end, the tubular member including a plurality of apertures formed in an outer surface thereof, and the inflation lumen is in fluid communication with the inflatable balloon through the apertures. 